1. Field of the Invention:
The present invention relates, generally, to welding torches used for gas-shielded metal arc welding and, specifically, to such a torch which incorporates dual shielding gas systems for improved protection of the weld area from atmosphere contamination and oxidation.
2. Description of the Prior Art:
In some electric arc welding processes, such as shielded metal arc (SMA) welding and gas metal arc (GMA) welding, filler metal is transferred from a consumable electrode, across the arc, to the weld puddle. In contrast, nonconsumable electrode processes, such as gas tungsten arc (GTA) welding, rely upon an auxiliary feed system to present filler metals to the weld. The filler metal is generally not transferred across the arc. The deposition rates and welding speeds for processes of the latter type are frequently inferior to the consumable electrode techniques.
During certain welding processes, such as in SMA welding, for example, atmospheric contaminants are excluded from the weld puddle by shielding gases and slag systems formed when a coaxial electrode coating decomposes. Because of the coaxial design of the electrodes, adequate shielding can usually be provided wherever the electrode can be inserted and manipulated.
In GMA welding, the torch is designed to carry and direct a consumable wire electrode and a shielding gas to the puddle area. The torch's size limits its usefulness in making weldments in confined areas.
There exists, therefore, a need for a GMA welding torch which can be used in difficult-to-reach locations which adequately shields the weld.